Devices such as valves for fluid control are often actuated and adjusted manually in industrial installations in the course of operation of various industrial processes such as petroleum refining, paper manufacture, mining, chemical production and waste water treatment plants to cite but a few examples. Manual adjustment of valves allows the industrial processes controlled by the fluid flow through the valves to be optimized for various factors such as product yield, throughput, reaction rate, as well as other parameters associated with the economics and efficiency of the processes.
It is desirable to incorporate refinements into the valve design that will allow for convenient setting of the valves to known positions providing fluid flow rates determined either theoretically or during operation of the industrial processes that produce the desired yield, reaction rate, throughput or other process parameters. Infinite variability of the setting is advantageous for precise tuning of system parameters.
Additional desirable refinements to valves also include the ability to lock the valve in the closed or open positions. Locking the valve in the closed position will help prevent mishaps during system maintenance, when portions of the system may be disassembled for replacement or repair. Locking the valve in the open position will help ensure that fluid flow is not halted inadvertently during operation. It is also advantageous to have the valve be tamper resistant to prevent unauthorized opening of the valve and thereby prevent theft of the product flowing through the system. The aforementioned refinements for devices such as valves may be effected using handle assemblies as described and claimed below.